1. Field of the Invention
The present disclosure relates to a light emitting device including a semiconductor light emitting element and a wavelength conversion layer, and to a method of manufacturing the same.
2. Description of Related Art
There has been a white diode configured to emit white light by combining an LED (light emitting diode) to emit blue light and a wavelength conversion layer (phosphor layer) which absorbs a portion of the blue light emitted from the LED and converts the light to light of a different wavelength such as yellow light, are used in combination so that white light can be produced by mixing the blue light and the yellow light.
A method of manufacturing the white light emitting diode includes a method of applying a resin containing a granular phosphor (wavelength conversion member) to an LED chip. For example, JP 2012-119673 A discloses a method by which many singulated LED chips are arranged apart from each other on a carrier substrate having a surface containing an adhesive agent, and a thermosetting resin containing a phosphor is applied onto an upper surface and a side surface of each of the LED chips by screen printing using a stencil mask. In addition, JP 2012-119673 A discloses a method by which the LED chips are arranged apart from each other on the carrier substrate, the thermosetting resin containing the phosphor is applied to the upper surface of each LED chip and between LED chips with a spray device, and singulated into individual pieces by dicing after the resin is cured.
Furthermore, JP 2003-69086 A discloses a method by which phosphor particles are uniformly attached on the LED chip by electrodeposition. That is, according to the method disclosed in JP 2003-69086 A, a wavelength conversion layer is formed by electrophoretically attaching the phosphor particles to the surface of the LED chip.
However, according to the method using the screen printing disclosed in JP 2012-119673 A, it is necessary to align the LED chips arranged on the carrier substrate with the stencil mask. Thus, if the LED chip is not correctly aligned with the stencil mask, it may result in occurrence of some regions where the wavelength conversion layer is not formed in the upper surface, and the wavelength conversion layer does not have a predetermined thickness on the side surface, so that uneven distribution of light color may occur. According to the other method, at the time of dicing the wavelength conversion layer applied to the LED chips, if the position to be diced is not accurate, the wavelength conversion layer provided on the side surface does not have a predetermined thickness, so that a distribution light color becomes uneven.
In addition, according to the method disclosed in JP 2003-69086 A, it has been difficult to form the wavelength conversion layer on a single LED chip body. If there can be prepared a supporting substrate of the LED chip having uniform in-plane electric resistance, it is theoretically possible to form a resin layer containing phosphor particles and having a uniform thickness by the electrodeposition, but it has been difficult to obtain the above supporting substrate. In addition, according to the method disclosed in JP 2003-69086 A, it is necessary to previously give electrical conductivity to an entire exposed surface of the LED chip to be used. Furthermore, according to the method using the electrophoresis, the element such as the LED chip needs to be soaked in an organic solvent for a long time, so that there are many restrictions in materials which can be used, and the method cannot be applied to various types of elements.